Fragmented ancestral gene clusters in the cpDNAs of UTC algae. The indicated clusters are found in both Mesostigma and Nephroselmis cpDNAs. Note that rpl22 has not been represented in the large ribosomal protein cluster because it is present only in Mesostigma cpDNA (between rps19 and rps3). Sites of fragmentation are denoted by arrowheads of different shades above the clusters: Chlamydomonas, filled arrowheads; Pseudendoclonium, dark grey arrowheads; Oltmannsiellopsis, light grey arrowheads; and Chlorella, open arrowheads. Genes missing from Chlamydomonas, Pseudendoclonium, Oltmannsiellopsis and Chlorella are indicated by squares, circles, asterisks and double dagger, respectively. Gene polarities are not shown.